The subject matter of this disclosure relates generally to fluid processing, and in particular to differential pressure devices for process flow measurement. Specifically, the invention concerns a differential pressure diagnostic for pressure pulsations in a fluid flow.
Pressure-based flow sensors provide utility across a wide range of industrial applications, including bulk fluid storage and transport, agriculture, environmental control, water and air distribution, food and beverage preparation, chemical and pharmaceutical production, and a range of manufacturing processes utilizing thermoplastics, glues, resins and other fluidic materials. Pressure measurements are also important to energy production and other hydrocarbon fuel applications, which involve a wide range of fluidic flows including natural gas, diesel, pulverized coal, water and steam.
Pressure sensing technologies range from simple spring gauges, strain gauges and other mechanical devices to advanced capacitive, piezoresistive and electrochemical sensors. In industrial systems, these are typically housed in a transmitter or other more generalized field device, which protects the sensor hardware and adds higher-order functionality such as signal processing and communications.
The most appropriate pressure measurement methods depend upon the properties of the process material and the demands of each particular processing application. In custody transfer, for example, differential pressure measurements are typically utilized to achieve flow sensitivity via Bernoulli's principle and other velocity-dependent effects. In energy production, on the other hand, gage and absolute pressure measurements are required to provide precision control of large-scale rotary equipment such as blowers, fans, compressors and turbines.
Many of these applications subject the process fluid to pressure pulsations, with frequencies ranging from a few Hertz to hundreds of Hertz or more. Process pulsations can substantially alter the relationship between measured differential pressure and flow rate, reducing operating efficiency and preventing process optimization. In custody transfer and other “cash-register” applications where pressure measurements are directly related to bottom line costs and revenue, pulsation-induced errors also have direct economic implications. As a result, there is a need for diagnostics that are sensitive to process pulsations over a wide frequency band, and applicable to an extensive range of fluid handling, fluid processing and fluid flow applications.